package main

import (
	"os"
	"encoding/csv"
	"fmt"
	"strconv"
	"sort"
	"time"
)

func main(){
	f, err := os.Open("./Environmental_Data_Deep_Moor_2015.txt")
	if err!=nil{
		panic(err)
	}
	defer f.Close()

	rdr := csv.NewReader(f)
	rdr.Comma = '\t'
	rdr.TrimLeadingSpace = true
	rows, err := rdr.ReadAll()
	if err!=nil{
		panic(err)
	}

	start:=time.Now()
	fmt.Println("Total record:", len(rows)-1)
	if len(rows)-1>0{
		fmt.Println("Mean Air Temparature:", mean(rows, 1))
		fmt.Println("Mean Barometric pressure:", mean(rows, 2))
		fmt.Println("Mean Wind Speed", mean(rows, 7))

		fmt.Println("Median Air Temparature:", median(rows, 1))
		fmt.Println("Median Barometric pressure:", median(rows, 2))
		fmt.Println("Median Wind Speed", median(rows, 7))
	}
	end:=time.Now()
	fmt.Println(end.Sub(start))
}

func mean(rows [][]string, idx int) float64{
	var total float64

	for i,row := range rows{
		if i!=0{
			val, _ := strconv.ParseFloat(row[idx],64)
			total+=val
		}
	}

	return total/ float64(len(rows)-1)
}

func median(rows [][]string, idx int) float64{
	var sorted[] float64

	for i,row := range rows{
		if i!=0{
			val, _ := strconv.ParseFloat(row[idx],64)
			sorted = append(sorted, val)
		}
	}

	sort.Float64s(sorted)

	middle := len(rows)/2

	if len(rows)%2==0{
		high := sorted[middle]
		low := sorted[middle-1]

		return (high+low)/2
	}

	return	sorted[middle]/2
}